It certainly won&apos;t match the level of national attention garnered before the first-in-the-nation caucuses last January, but Iowa is about to reprise its status as an early barometer of the presidential race. On Thursday, Iowa will become the first swing state to begin early voting. Once it has been gradually rolled out nationwide, early voting is expected to be even more consequential than was the case four years ago -- perhaps all but foretelling the winner of the presidential race before Election Day comes around on Nov. 6. For months, staffers and volunteers at the Obama...